Convert between Gregorian calendar dates and Julian Day Numbers (JDN) used in astronomy. Also computes Modified Julian Date (MJD) and Easter Sunday.
JDN 0 = 1 January 4713 BC (Julian calendar) = 24 November 4714 BC (Gregorian)
JDN 2451545 = 1 January 2000 (J2000.0 epoch)
MJD = JDN − 2400000.5 (starts at midnight, not noon)
marduc812
2026